Tubular electric incandescent lamp



June 1, 1937,

Filed May 1, 1955 m c L 9 Q Q Q Q x h. b Q n UH. O n W R, N Q R, N W Q, Q Q R, M W Q M H... Q Q. Q i m Q Q N ?atented June 1, 1937 UNITED STATES PATENT OFFICE Paul 0. Cartun, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New York Application May 1, 1935, Serial No. 19,238

4 Claims.

filed April 20, 1933, Patent No. 2,032,791, discloses a lamp consisting of an elongated tubular glass bulb having a metal disc sealed to each end thereof as an end -wall and terminal and a filament extending longitudinally substantially the entire-length of said bulb and electrically connected at each end to one of said metal discs. The lamp according to the present invention is preferably somewhat similar in design. However, there are some cases in which it is desirable to provide a plurality of filaments in multiple rather than a single long filament; for example, where the lamp is extremely long, or where the lamp is used on low voltages, such as 30 volts. The several filaments may then be made of coarser or heavier wire than a single long filament operating on the same voltage. The present invention deals with such a multiple filament lamp having a simple but sturdy supporting structure for the filaments. One of the features of my invention is the use of a channel-shaped stay to provide rigidity, lightness and strength in the supporting structure for the filament. This feature is applicable to single filament lamps as well as multiple filament lamps.

Further features and advantages of my invention will appear from the following description of species thereof.

In the drawing, Fig. 1 is a side view of a twofilament lamp comprising my invention; Figs. 2 and 3 are side and top views respectively of a modified two-filament lamp; and Fig. 4 is a side view of a single filament lamp in which is incorporated my improved filament supporting structure.

Referring to Fig. l, the lamp comprises a tubular bulb Ill having terminal members consisting of metal discs I I, ll sealed to the ends thereof as end walls and contacts. The particular discs shown are of the type disclosed in pending application Serial No. 3,334, Harold D. Blake, filed January 24, 1935, and have central annular recesses or depressions l2 therein which are engaged by suitable holders for mounting the lamp and conducting current thereto. One of the discs H has an opening 13 at the center thereof through which the bulb I0 is exhausted, the said opening being sealed after exhaustion by a glass mass I 4. A pair of filaments l5, l6 are located in the bulb Ill and extend longitudinally thereof in end to end relation substantially the entire length of said bulb. The supporting and current conducting structure for said filaments comprises a pair of stays l1, l8, in this instance consisting of metal channels, extending longitudinally of the bulb ill co-extensively with the filaments l5, l6 respectively and adjacent the wall of the bulb. The said channels ll, l8, as well as the discs I I, a are preferably made of an iron alloy containing about twenty-nine per cent of chromium, such as an alloy marketed by the Allegheny Steel Company as Allegheny 55 and described specifically in my patent application hereinbefore referred to. The adjacent ends of said channels are sealed in an insulating bead l9, such as glass, located substantially at the center, longitudinally, of the bulb ill. The opposite or remote ends of said channel-shaped stays l1, l8 are each secured to one end of each of a pair of wires 20, 2|, the opposite ends of which terminatein loops surrounding the shoulders formed at the inside of the discs H by the depressions l2 therein. Short transversely extending lengths of wire 22, 23 are secured to the wires 20, 2| respectively and the remote ends of each of the filaments l5, l6 are secured to the said wires 22, 23 respec-. tively. The opposite or adjacent ends of the filaments l5, it are secured to wires 24, 25 respectively which are in turn secured to the adjacent ends of the stays l8 and i1 respectively. The filaments are supported at intermediate points by wires 26 each of which has an end embedded in an insulating head 21 sealed to the stay H or l8. The circuits are therefore from left hand disc ll through wires 20, 22, filament l5, wire 24, stay 18, wire 2i, to right hand disc II, and from left hand disc ll through wire 20, stay l1, wire 25, filament l6, wires 23, 2| to right hand disc II.

In the modified lamp shown in Figs. 2 and 3, the contact discs i i are of a type shown in my patent application referred to hereinbefore and having outward protuberances 28 forming external shoulders adapted to be engaged by suitable holders. The stays l8 in this case each consist of a length of wire having a loop at its remote end engaging the internal shoulder at the inside of each disc it formed by the protuberance 28. The said stays l1, l8 extend longitudinally of the bulb l adjacent the wall to the middle thereof where the adjacent ends 29, 30 are bent in toward the axis of the bulb.

The filament I5 is secured at its remote end to the wire 22 and at its adjacent end to the bent end of stay i8. The filament i6 is secured at its remote end to the wire 23 and at the other end to the bent end of stay ll. The bent adjacent ends of the stays I'I, I8 are held in spaced relation by an insulating bead l9 sealed around portions thereof.

Fig. 4 shows a supporting structure for a single filament lamp incorporating a channel-shaped l5 stay 3| which is similar to the stays l7 and I8 in Fig. 1 and extends nearly the entire length of the bulb Ill. One end of the said stay 3| is secured to the wire 2| which in turn is secured to the adjacent disc I I. The opposite end of said stay is embedded in one end of a short glass rod or bead 32, an end of the wire 20 being embedded in the opposite end of said glass rod. The rod or bead 32 is necessary to prevent a short-circuit between the discs ll. 25, extends substantially the entire length of the bulb I0 is supported at intermediate points by the support wires 26 which are in turn secured.

to the stay 3| through the glass beads 27.

What I claim as new and desire to secure by 30 Letters Patent of the United States is:

1. In an incandescent lamp, a tubular bulb, a pair of filaments extending longitudinally of said bulb in end to end relation, a metal terminal member secured to each end of said bulb, the

remote end of each of said filaments being electrically connected to the adjacent terminal member, a pair of conductive stays each longitudinally coextensive with one of said filaments, each of said stays being electrically connected at its remote end to the adjacent terminal member and each of 2. In an incandescent lamp, a tubular bulb, a

pairof filaments extending longitudinally of said bulb in end to end relation, a metal terminal member secured to each endvof said bulb, the remote end of each of said filaments being electri- The filament 33, which cally connected to the adjacent terminal member, a pair of conductive stays each longitudinally coextensive with one of said filaments, insulating means for holding the adjacent ends of said stays in spaced relation, each of said stays being electrically connected at its remote end to the adjacent terminal member and each of the adjacent ends of said stays being electrically connected to the adjacent end of the filament which is coextensive with the other stay whereby said filaments are electrically connected in multiple between said terminals. g

3. In an incandescent lamp, a tubular bulb, a pair oi. filaments extending longitudinally of said bulb in end to end relation, a metal terminal member secured to each end of said bulb, the remote end of each of said filaments being electrically connected to the adjacent terminal member, a pair of conductive stays each longit 'dinally co-extensive with one of said filaments, ins ating means for holding the adjacent ends of said stays in spaced relation, each of said stays being electrically connected at its remote end to the adjacent terminal member and each of the adjacent ends of said stays being electrically connected to the adjacent end of the filament which is coextensive with the other stay whereby said filaments are electrically connected in multiple between said terminals and support wires engaging said filaments at intermediate points and secured to but insulated from said stays;

4. In an incandescent lamp, a tubular bulb, a pair of filaments extending longitudinally of said bulb in end to end relation, a metal terminal member secured to each end of said bulb, the remote end of each of said filaments being electrically connected to the adjacent terminal member, a pair of channel-shaped metal stays each longitudinally co-extensive with one of said filaments. insulating means for holding the adjacent ends of said stays in spaced relation, each of said stays being electrically connected at its remote end to the adjacent terminal member, and a conductor secured at one end to one of the adjacent ends of each of said stays and at the other end to the adjacent end of the filament which is co-extensive with the other stay whereby said filaments are electrically connected in multiple between said terminals.

- ram. 0. CARTUN. 

